Replicant is a FOSSoperating system based on the Android mobile platform, which aims to replace all proprietary Android components with their free software counterparts. It is available for several smartphones and tablet computers.[1][2][3][4] In March 2014, the Replicant project announced the discovery of a backdoor present in a wide range of Samsung Galaxy products that allows the baseband processor to read and write the device's storage,[5][6] sometimes with normal user privileges and sometimes as the root user, depending on device model.[7] It is not generally known whether Samsung's proprietary firmware for the radio chip can be remotely instructed to use these access features and the intentions of creating such a backdoor.

Subgraph is a Linux-based operating system designed to be resistant to surveillance and interference by sophisticated adversaries over the Internet. Subgraph OS is designed with features which aim to reduce the attack surface of the operating system, and increase the difficulty required to carry out certain classes of attack. This is accomplished through system hardening and a proactive, ongoing focus on security and attack resistance. Subgraph OS also places emphasis on ensuring the integrity of installed software packages through deterministic compilation. Subgraph OS features a kernel hardened with the Grsecurity and PaX patchset, Linux namespaces, and Xpra for application containment, mandatory file system encryption using LUKS, resistance to cold boot attacks, and is configured by default to isolate network communications for installed applications to independent circuits on the Tor anonymity network.[citation needed]

Tails is a security-focused Linux distribution aimed at preserving privacy and anonymity.[8]

Whonix[9][10] is an anonymous general purpose operating system based on VirtualBox, Debian GNU/Linux and Tor. By Whonix design, IP and DNS leaks are impossible. Not even Malware as Superuser can find out the user's real IP address/location. This is because Whonix consists of two (virtual) machines. One machine solely runs Tor and acts as a gateway, called Whonix-Gateway. The other machine, called Whonix-Workstation, is on a completely isolated network. Only connections through Tor are possible.

Qubes OS is a desktop operating system based around the Xenhypervisor that allows grouping programs into a number of isolated sandboxes (virtual machines) to provide security. Windows for programs running within these sandboxes ("security domains") can be color coded for easy recognition. The security domains are configurable, they can be transient (changes to the file system will not be preserved), and their network connection can be routed through special virtual machines (for example one that only provides Tor networking). The operating system provides secure mechanisms for copy and paste and for copying files between the security domains.[11]

Annvix was originally forked from Mandriva to provide a security-focused server distribution that employs ProPolice protection, hardened configuration, and a small footprint. There were plans to include full support for the RSBACmandatory access control system. However, Annvix is dormant, with the last version being released on 30 December 2007.[13]

EnGarde Secure Linux is a secure platform designed for servers. It has had a browser-based tool for MAC using SELinux since 2003. Additionally, it can be accompanied with Web, DNS, and email enterprise applications, specifically focusing on security without any unnecessary software. The community platform of EnGarde Secure Linux is the bleeding-edge version freely available for download.[citation needed]

Immunix was a commercial distribution of Linux focused heavily on security. They supplied many systems of their own making, including StackGuard; cryptographic signing of executables; race condition patches; and format string exploit guarding code. Immunix traditionally releases older versions of their distribution free for non-commercial use. The Immunix distribution itself is licensed under two licenses: The Immunix commercial and non-commercial licenses. Many tools within are GPL, however; as is the kernel.[citation needed]

TrustedBSD is a sub-project of FreeBSD designed to add trusted operating system extensions, targeting the Common Criteria for Information Technology Security Evaluation (see also Orange Book). Its main focuses are working on access control lists, event auditing, extended attributes, mandatory access controls, and fine-grained capabilities. Since access control lists are known to be confronted with the confused deputy problem, capabilities are a different way to avoid this issue. As part of the TrustedBSD project, there is also a port of NSA's FLASK/TE implementation to run on FreeBSD. Many of these trusted extensions have been integrated into the main FreeBSD branch starting at 5.x.

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These operating systems are all engineered around the object-capabilities security paradigm, where instead of having the system deciding if an access request should be granted the bundling of authority and designation makes it impossible to request anything not legitimate.

Trusted Solaris was a security-focused version of the Solaris Unix operating system. Aimed primarily at the government computing sector, Trusted Solaris adds detailed auditing of all tasks, pluggable authentication, mandatory access control, additional physical authentication devices, and fine-grained access control. Trusted Solaris is Common Criteria certified.[15][16] The most recent version, Trusted Solaris 8 (released 2000), received the EAL4 certification level augmented by a number of protection profiles. Telnet was vulnerable to buffer overflow exploits until patched in April 2001.[17]

Starting with Windows Server 2008, Windows Server has added an installation option called "Server Core", in which the traditional graphical user interface is not installed. Administration, in Windows Server 2008, should rely on Windows Command Prompt. Roles and components are then installed individually. This option reduces the Windows Server footprint, the result of which is reduced demand on system resources and reduced number of components that could potentially be exploited via potential security vulnerabilities.[18]

Later, with Windows Server 2016, Microsoft introduced a Nano Server installation option with even more reduced footprint. It is headless and does not support a locally connected keyboard and monitor.[19] Nano Server in Windows Server 1709 (the constantly updated sibling of Windows Server 2016) can only be installed in a container.[20]